Long Term Debt (Senior Unsecured Debt) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 19, 2018
Debt Instrument [Line Items]
Principal Outstanding	$ 17,155	$ 17,400
Secured Debt [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 5,350	5,246
Secured Debt [Member] | Term Loan Due 3/31/2021 [Member]
Debt Instrument [Line Items]
Principal Outstanding		$ 1,402
Interest Rate		5.28%
Debt instrument, maturity date	Mar. 31, 2021
Secured Debt [Member] | Term Loan Due 10/12/2021 [Member]
Debt Instrument [Line Items]
Principal Outstanding		$ 239
Interest Rate		7.405%
Debt instrument, maturity date	Oct. 12, 2021
Secured Debt [Member] | Revolver Due 2/27/2024 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 375	$ 275
Interest Rate	5.488%	5.28%
Debt instrument, maturity date	Feb. 27, 2024
Secured Debt [Member] | Term Loan Due 6/15/2024 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 1,712	$ 1,716
Interest Rate	6.25%	6.28%
Debt instrument, maturity date	Jun. 15, 2024
Secured Debt [Member] | First Lien Notes Due 4/1/2027 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 1,650
Interest Rate	8.00%
Debt instrument, maturity date	Apr. 01, 2027
Secured Debt [Member] | Second Lien Notes Due 4/1/2026 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 1,600	$ 1,600
Interest Rate	8.50%	8.50%	8.50%
Debt instrument, maturity date	Apr. 01, 2026
Secured Debt [Member] | IDRB Due 5/1/2030 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 13	$ 13
Interest Rate	6.20%	6.20%
Debt instrument, maturity date	May 01, 2030
Secured Debt [Member] | Equipment Financings [Member]
Debt Instrument [Line Items]
Principal Outstanding		$ 1
Interest Rate		0.00%
Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 10,949	$ 11,297
Unsecured Debt [Member] | Senior Note Due 3/15/2019 [Member]
Debt Instrument [Line Items]
Principal Outstanding		$ 348
Interest Rate		7.125%
Debt instrument, maturity date	Mar. 15, 2019
Unsecured Debt [Member] | Senior Note Due 4/15/2020 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 172	$ 172
Interest Rate	8.50%	8.50%
Debt instrument, maturity date	Apr. 15, 2020
Unsecured Debt [Member] | Senior Note Due 9/15/2020 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 55	$ 55
Interest Rate	8.875%	8.875%
Debt instrument, maturity date	Sep. 15, 2020
Unsecured Debt [Member] | Senior Note Due 7/1/2021 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 89	$ 89
Interest Rate	9.25%	9.25%
Debt instrument, maturity date	Jul. 01, 2021
Unsecured Debt [Member] | Senior Note Due 9/15/2021 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 220	$ 220
Interest Rate	6.25%	6.25%
Debt instrument, maturity date	Sep. 15, 2021
Unsecured Debt [Member] | Senior Note Due 4/15/2022 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 500	$ 500
Interest Rate	8.75%	8.75%
Debt instrument, maturity date	Apr. 15, 2022
Unsecured Debt [Member] | Senior Note Due 9/15/2022 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 2,188	$ 2,188
Interest Rate	10.50%	10.50%
Debt instrument, maturity date	Sep. 15, 2022
Unsecured Debt [Member] | Senior Note Due 1/15/2023 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 850	$ 850
Interest Rate	7.125%	7.125%
Debt instrument, maturity date	Jan. 15, 2023
Unsecured Debt [Member] | Senior Note Due 4/15/2024 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 750	$ 750
Interest Rate	7.625%	7.625%
Debt instrument, maturity date	Apr. 15, 2024
Unsecured Debt [Member] | Senior Note Due 1/15/2025 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 775	$ 775
Interest Rate	6.875%	6.875%
Debt instrument, maturity date	Jan. 15, 2025
Unsecured Debt [Member] | Senior Note Due 9/15/2025 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 3,600	$ 3,600
Interest Rate	11.00%	11.00%
Debt instrument, maturity date	Sep. 15, 2025
Unsecured Debt [Member] | Debenture Due 11/1/2025 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 138	$ 138
Interest Rate	7.00%	7.00%
Debt instrument, maturity date	Nov. 01, 2025
Unsecured Debt [Member] | Debenture Due 8/15/2026 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 2	$ 2
Interest Rate	6.80%	6.80%
Debt instrument, maturity date	Aug. 15, 2026
Unsecured Debt [Member] | Senior Note Due 1/15/2027 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 346	$ 346
Interest Rate	7.875%	7.875%
Debt instrument, maturity date	Jan. 15, 2027
Unsecured Debt [Member] | Senior Note Due 8/15/2031 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 945	$ 945
Interest Rate	9.00%	9.00%
Debt instrument, maturity date	Aug. 15, 2031
Unsecured Debt [Member] | Debenture Due 10/1/2034 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 1	$ 1
Interest Rate	7.68%	7.68%
Debt instrument, maturity date	Oct. 01, 2034
Unsecured Debt [Member] | Debenture Due 7/1/2035 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 125	$ 125
Interest Rate	7.45%	7.45%
Debt instrument, maturity date	Jul. 01, 2035
Unsecured Debt [Member] | Debenture Due 10/1/2046 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 193	$ 193
Interest Rate	7.05%	7.05%
Debt instrument, maturity date	Oct. 01, 2046
Secured Subsidiary Debt [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 106	$ 107
Secured Subsidiary Debt [Member] | Debenture Due 11/15/2031 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 100	$ 100
Interest Rate	8.50%	8.50%
Debt instrument, maturity date	Nov. 15, 2031
Secured Subsidiary Debt [Member] | RUS Loan Contracts Due 1/3/2028 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 6	$ 7
Interest Rate	6.154%	6.154%
Debt instrument, maturity date	Jan. 03, 2028
Unsecured Subsidiary Debt [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 750	$ 750
Unsecured Subsidiary Debt [Member] | Debenture Due 5/15/2027 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 200	$ 200
Interest Rate	6.75%	6.75%
Debt instrument, maturity date	May 15, 2027
Unsecured Subsidiary Debt [Member] | Debenture Due 2/1/2028 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 300	$ 300
Interest Rate	6.86%	6.86%
Debt instrument, maturity date	Feb. 01, 2028
Unsecured Subsidiary Debt [Member] | Debenture Due 2/15/2028 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 200	$ 200
Interest Rate	6.73%	6.73%
Debt instrument, maturity date	Feb. 15, 2028
Unsecured Subsidiary Debt [Member] | Debenture Due 10/15/2029 [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 50	$ 50
Interest Rate	8.40%	8.40%
Debt instrument, maturity date	Oct. 15, 2029
Secured Debt, Unsecured Debt, Secured Subsidiary Debt, And Unsecured Subsidiary Debt [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 17,155	$ 17,400
Interest Rate	8.651%	8.411%